ByBen McConville, Associated PressMarch 29, 2012

This is an undated handout photo issued by Total E&P UK Ltd of Total's Elgin PUQ (Process/Utilities/Quarters) platform. A two-mile exclusion zone has been set up around the offshore platform in the North Sea which has been evacuated after a gas leak, Tuesday, March 27. The leak on Total's Elgin PUQ platform, about 150 miles off the coast of Aberdeen, led to the evacuation of all 238 workers on Sunday.

Edinburgh, Scotland — Environmental groups warned Thursday they fear an oil spill could be triggered at a North Sea offshore platform that has been leaking highly pressurized gas since the weekend.

A flame is still burning in the stack above the Elgin platform, which stands about 150 miles (240 kilometers) off the coast of Aberdeen, eastern Scotland, after a leak of flammable gas Sunday— prompting all 238 staff to be evacuated on Monday.

Platform operator Total S.A. insists there is no threat of any explosion under current weather conditions, but said that surveillance flights have detected a sheen around the platform estimated to extend over 4.8 square kilometers (1.85 square miles).

"Elgin is sending methane into the atmosphere, which is a greenhouse gas, so there is some environmental impact at the moment. There is also oil in that well, and Total need to move before an oil spill becomes part of this leak," said Richard Dixon, director of WWF Scotland.

He warned that any major spill would have "catastrophic consequences for the environment, marine life and sea birds in Shetland, the Faroe Islands and the Norwegian coast."

Total spokesman Jacques Emmanuel Saulnier has said the situation is serious but stable, and confirmed that the cause of the leak is still being investigated.

An exclusion zone of two nautical miles (2.3 miles; 3.7 kilometers) has been set up around Elgin, with ships and aircraft ordered to stay away from the area.

The leak came in the same week that the U.K. oil and gas industry announced it had begun exploration in the deep waters of the North Atlantic to the west of the Shetland Isles, off the Scottish coast. Campaigners have warned that the Elgin incident is a reminder of the dangers posed by deep water exploration and extraction.

"The U.K. industry, unions and regulatory authorities say they have the best and tightest safety regime in the world, but this leak proves that for all their efforts it remains unsafe," said Charlie Kronick, a senior climate adviser at Greenpeace U.K.

"The industry is trying to squeeze out the very last of the Earth's reserves and companies such as Total, BP and Royal Dutch Shell are pushing themselves into exploration that is extremely difficult, costly and risky," he said.

Dixon also raised worries about new exploration. "There is a big contradiction as Scotland has some of the toughest targets on climate change and renewable energy, which is great, but at the same time London and Edinburgh cozy up to the oil and gas industry," he said.

Scotland's governing Scottish National Party, which is seeking to hold a referendum on independence for Scotland by 2014, has put the oil industry at the heart of its economic plans — a stance which has also angered campaigners. "We should accept that we are at the end of the oil and gas age," said Kronick.

Britain tightened its offshore health and safety policies after the Piper Alpha disaster in 1988 when 167 workers died in a platform blast in the North Sea.